*{
  box-sizing: border-box;
}

h2{
  margin: 0;
  font-size: 1.1em;
  font-weight: normal;
  cursor: pointer;
  transition: background-color 0.3s;
}

ul{
  list-style: none;
  margin: 0;
  padding: 0;
}

.container{
  width: 200px;
  margin: 50px auto;
  line-height: 30px;
  h2{
    background-color: coral;
    padding-left: 20px;
    &.active {
      background-color: #ff6347;
    }
    
    &:hover {
      background-color: #ff7f50;
    }
  }
  .item{
    margin: 20px 0;
    .sub-menu{
      background-color: rgb(253, 148, 109);
      padding-left: 30px;
      // transition: height 0.3s;
      height: 0;
      overflow: hidden;
    }
  }
}